Once upon a time, I was dating a girl and she asked me, “do you switch?” And I replied, “no, I’m a righty.” Thinking I don’t switch hit, or throw with my left hand. I don’t think that was the answer she was looking for. What exactly did she mean by “switch”?
What you are likely suffering from iss an over-used sports metaphor. Lesbians are big fans of softball. Many will use softball terminology when talking about sex. For instance, tops can be referred to as “pitchers” while bottoms can be referred to as “catchers.” Women who do both are considered “versatile.” This is equally true for gay men.
What your girlfriend was probably asking was whether you consider yourself a bisexual. Depending on the context, “switch-hitting” or “playing for the other team” are terms often used by lesbians for women who sleep with men, either in addition to sleeping with women (switch) or exclusively (other team). Women playing for “our team” are lesbians.
Be careful, though. If you are hitting on your softball coach, or any softball coach, and you tell her you’re a pitcher, you just might find yourself out on the mound – probably not the mound you were hoping for – getting line drives pounded at your head.